Leaders of the Senate Select Committee on Intelligence said yesterday that national security affairs adviser Robert C. McFarlane assured them that members of his staff did not violate a congressional ban by giving military and fund-raising advice to Nicaraguan insurgents.

Sens. David F. Durenberger (R-Minn.) and Patrick J. Leahy (D-Vt.), after an hour-long briefing by McFarlane, told reporters that President Reagan had directed the White House staff to comply with the so-called Boland amendment cutting off Central Intelligence Agency aid to the insurgents.

Contacts between White House officials and the insurgents, known as contras, were limited to "what they felt was a normal moralization effort, if you will, to keep up the spirits of the opposition," Durenberger said.

This included "encouraging them to take their case to a broader public, to travel more, to make speeches," he said.

But the senators said they will look further into press reports that Lt. Col. Oliver North of the National Security Council staff also advised insurgent leaders on military tactics and steered contributors to them. A key fund-raiser for the contras, retired Army major general John K. Singlaub, has said he frequently talked to North about his fundraising efforts.

Leahy said he and Durenberger told McFarlane they would consider fund solicitation by an NSC official a violation of the letter and spirit of the congressional ban. McFarlane assured them North had done nothing beyond directing callers to the public offices of the contras.

"You can say that Bud McFarlane told us the truth as he understands it," Durenberger said. "I can't be 100 percent confident that that's all that really went on . . . . We're continuing an inquiry."

The senators also said they want to know more about the future relationship between the NSC and CIA and the contras now that Congress has approved $27 million in humanitarian aid for the troops fighting the Sandinista government of Nicaragua.

"We're not satisfied we know the ground rules under which the CIA will operate" whenever the ban ends, Durenberger said.

"We need to know what are the rules the CIA's going to live by. Are they going to go out there talking to the Singlaubs and so forth, and if so under what circumstances?" he added. "And what is the role of the NSC going to be?"

Durenberger said the Senate committee was starting out "a little more suspicious than maybe we ought to be, but appropriately so because at various places in the administration, policy has been implemented on an individual basis rather than on some kind of institutional basis."